Fan spacer and method for making same



I April 28, 1970 R. D. BRODERICK FAN SPACER AND METHOD FOR MAKING SAME Filed Jan. 24, 1968 3 Sheets-Sheet 1 INVENTOR. iaZarz JjraZerz/a? APril 23, 1970 R. D". BRODERICK 3,508,427

FAN SPACER AND METHOD FOR MAKING SAME Filed Jan. 24, 1968 I5 Sheets-Sheet 2 7; y 2 if I i 77 U W I I Z? INVENTOR.

FoZcrz J Bra/aria? Ap i 1970' R. D. BRODERICK 3,503,427

FAN SPACER AND METHOD FOR MAKING SAME Filed Jan 24, 1968 5 Sheets-Sheet s I I'l |lz III XV/j i |1 /14 MIX /fli 4 #4 FJEZTF.

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United States Patent O 3,508,427 FAN SPACER AND METHOD FOR MAKING SAME Robert D. Broderick, Birmingham, Mich., assignor to Detroit Gasket & Manufacturing Company, a corporation of Delaware Filed Jan. 24, 1968, Ser. No. 700,262 Int. Cl. B21c 23/00 US. Cl. 72-254 6 Claims ABSTRACT OF THE DISCLOSURE An integrally formed fan spacer for mounting a fan in spaced axial relationship on a driving member and a method for forming the fan spacer by extrusion in a manner to provide a centrally extending pilot bore and a cylindrical pilot projection at opposite end faces thereof and a plurality of longitudinally-extending, circumferentially-spaced through-bolt holes.

BACKGROUND OF THE INVENTION Variations in the distance between the Water pump pulley and hub assembly and the rear surface of the radi-.

ator core of passenger automobiles has heretofore been compensated by employing a diecast or other machined or cast spacer member of an appropriate length, to which the fan is adapted to be secured. Variations in the appropriate length of such a spacer member as a result of different engine options and accessory equipment has necessitated a relatively high investment in tooling and equipment to manufacture fan spacers of each of the several lengths required. In order to assure the proper alignment of the axis of rotation of the fan and the water pump shaft, careful machining operations of such fan spacers has heretofore been necessary which has still further increased the cost of such components.

In accordance with the fan spacer and method for manufacturing the fan spacer comprising the present invention, a substantial simplification in the design and manufacture of fan spacers is achieved, reducing the investment in expensive tooling, as well as obviating final machining operations, thereby substantially increasing the ease and versatility of manufacture, as well as achieving a substantial reduction in the cost of the component.

SUMMARY OF THE INVENTION The foregoing and other benefits of the present invention are achieved by the process comprising the present invention in which a billet of an extrudable metal is extruded into a rod of indefinite length and of a substantially uniform cross section in which a centrally extending pilot bore is formed in addition to a plurality of circumferentially and radially spaced apertures or throughbolt holes. The resultant rod is thereafter cut into blanks of preselected length, forming end faces which are disposed substantially perpendicular to the longitudinal axis of the blank. The resultant blank is thereafter placed in a mold wherein it is laterally confined and the material adjacent to the centrally extending bore is cold extruded in an axial direction inwardly of one face of the blank, effecting the formation of an integral cylindrical projection extending outwardly and concentrically of the other end face, whereafter the resultant integrally formed blank is coined by compacting the end faces, placing them in substantial parallelism to each other. The resultant fan spacer is in final finished form and is of accurate dimensions, necessitating no further final finishing operations. In accordance with this technique, fan spacers of the type hereafter described, can readily bemade in various different prescribed lengths by simply cutting the continuous 3,508,427 Patented Apr. 28, 1970 rod into blanks of different lengths and employing appropriately-sized confining molds.

Additional benefits and advantages of the fan spacer and the process for manufacturing the fan spacer will become apparent upon a reading of the preferred embodiments of this invention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 2 is a fragmentary side elevational View, partly in section, illustrating a typical installation in an engine coling system of af an spacer between a fan and the mounting face of a pulley and hub assembly of a water P p;

FIGURE 2 is an enlarged end view of a fan spacer of the type shown in FIGURE 1;

FIGURE 3 is a vertical longitudinal sectional view of the fan spacer shown in FIGURE 2 and taken substantially along the line 33 thereof;

FIGURE 4 is a fragmentary vertical sectional view of the extrusion step in which the blank is peripherally restrained within a mold;

FIGURE 5 illustrates a coining of the end faces of the blank to achieve substantial parallelism thereof;

FIGURE 6 is a fragmentary vertical sectional view of an alternate satisfactory die assembly for effecting a cold extrusion of the blank; and

FIGURE 7 is a vertical longitudinal sectional view of the fan spacer made in accordance with the die assembly shown in FIGURE 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical installation of a fan spacer 8 is illustrated in FIGURE 1 of the drawings in which it is adapted to be disposed between a fan, fragmentarily shown at 10, and the front end of a hub 12, on which a bell-shaped pulley '14 is mounted. The hub 12 is securely affixed to the end of a shaft 16, which is rotata-bly supported by means of a bearing 18 secured in the forward end of a water pump housing 20. The rearward or right-hand end of the shaft 16, as viewed in FIGURE 1, extends through a water pump seal assembly 22 and an impeller 24 is affixed to the end thereof.

The fan 10 is secured by means of through-bolts screws 26, the shanks of which extend through apertures or bolt holes 28 formed in the fan spacer 8, and the ends thereof are disposed in threaded engagement in threaded bores 30 formed at circumferentially-spaced intervals in the annular flange of the hub 12. The forward face of the hub 12 is disposed in a plane substantially perpendicular to the axis of the shaft 16, whereby a fan mounted thereagainst will similarly rotate in a substantially perpendicular plane, avoiding thereby the imposition of any gyroscopic stresses and/or vibrations as a result of a misalignment between the fan blades and the shaft. Similarly, it is important, when the fan spacer 8 is employed, that the end faces thereof, indicated at 32 and 34, respectively, in FIGURES l and 3, are in substantial parallelism to each other to maintain this relationship. Generally, a degree of parallelism of within 0.003-inch is considered satisfactory for most installations.

Alignment of the fan 10 on the face of the hub 12 is achieved by the piloting coaction between the projecting end of the shaft 16 and an aperture 36 formed in the center of the fan. When a fan spacer, such as the fan spacer 8, is employed, this alignment relationship is retained by means of a pilot bore 38, extending inwardly of the end face 32 which is adapted to engage the projecting end of the shaft 16 and a tubular projection 40 extending outwardly of the end face 34, which is adapted to be disposed in sliding relationship within the aperture 36 of the fan.

The foregoing installation, as illustrated in FIGURE 1, is typical of that employed in automobiles equipped with a liquid cooled internal combustion engine and a conventional cooling system including a radiator disposed forwardly of the fan, through which the coolant is circulated by the pump from the passageways or jackets within the engine. Rotation of the assembly is conventionally achieved by a suitable V-belt trained about the pulley 14, which is driven by a drive pulley (not shown) affixed to the forward end of the crankshaft. By virtue of employing the fan spacer, optimum positioning of the fan relative to the radiator can be achieved consistent with the specific baflling or shrouding arrangement employed, as well as for accommodating the incorporation on some models of a thermostatically-controlled jfan clutch of the types well known in the art.

In the light of the foregoing, it will be apparent that the fan spacer must not only be of high strength to sustain the concurrent rotational and compressive forces imposed thereon, as well as vibrational stresses during operation, but must also be of accurate size to assure the maintenance of the fan in a plane of rotation substantially perpendicular to the axis of the supporting shaft. An integrally-formed fan spacer possessing these properties and which is of simple and economical manufacture in accordance with the process comprising the present invention is best illustrated in FIGURES 2 and 3. The spacer comprises a body including a central tubular boss 42 having a plurality of longitudinally-extending and radially-projecting webs 44 integrally afiixed to the periphery thereof. The outer portion of each of the webs 44 is formed with a tubular boss 46 which defines the aperture or bolt hole 28 for receiving the shank of a through-bolt 26 (FIGURE 1). As best seen in FIGURE 3, the pilot bore 38 is of a diameter greater than that of the central bore 48 and is adapted to correspond substantially to that of the shaft (FIGURE 1) of a water pump on which it is to be mounted. The intersection of the axially aligned concentric bores 38 and 48 forms an annular shoulder, indicated at 52 in FIGURE 3.

Further rigidification of the spacer adjacent to the bolt holes 28 is provided by a pair of longitudinally-extending circumferentially-projecting ears or flanges 54 integrally aflixed to each of the tubular bosses 46, as best seen in FIGURE 2. The flanges 54 prevent distortion of the end faces 32, 34 relative to each other as the result of the compressive stresses imposed therebetween in response to a tightening of the through-bolts 26 (FIGURE 1) during installation, thereby assuring a continued parallelism between the end faces.

With reference to FIGURE 3, the length of the tubular projection 40 is controlled so as to provide satisfactory piloting of an aperture formed in the center of the fan during installation, as well as during operation thereof. The projecting end of the tubular projection can be chamfered, as at 56, to facilitate initial alignment of a fan during installation. Similarly, the depth of the pilot bore 38 is controlled so as to extend for a distance greater than the projecting end of the water pump shaft (FIG- URE 1) which is adapted to be slidably received therein. The actual depth of the pilot bore 38 is dependent to some extent on the cold extrusion technique subsequently to be described.

The manufacture of the fan spacer, as hereinbefore described, can be simply and economically achieved by the extrusion of a suitable metal or metal alloy possessing cold extrusion properties. For this purpose, alloys of aluminum have been found particularly suitable, of which type 6063 aluminum alloy constitutes a preferred material This alloy is generally designated as a silicon-magnesium aluminum alloy nominally containing 0.200.60% silicon, OAS-0.90% magnesium, with the balance essentially aluminum including minor amounts of iron, copper, manganese, chromium, nickel, zinc, titanium and other conventional impurities. This alloy, in addition to possessing good extrusion properties, also is heat treatable and possesses good corrosion resistance and an ultimate tensile strength of about 33,000 p.s.i. in the heat treated condition. Alternative satisfactory alloys possessing the necessary properties to provide extrusion of the spacer blank can be employed for this purpose to provide a resultant fan spacer of the requisite strength.

In accordance with the process comprising the present invention, a billet or pig of the metal alloy is extnlded into a rod of indefinite length having, a substantially constant transverse cross section such as the cross section illustrated in FIGURE 2 and incorporating the longitudinally-extending bolt holes 28 and central bore 48 therethrough. At the completion of the extrusion operation, the rod, if of an appropriate alloy, can be subjected to the prescribed heat treatment, after which the rod is cut into individual blanks of the requisite length consistent with the size spacer 'to be formed. Alternatively, the heat treatment can be delayed and performed on the finished fan spacer. The blank, such as a blank 58, shown in FIGURE 4, is thereafter slidably disposed in a mold 60 provided with a cavity corresponding substantially to the peripheral contour of the blank. The blank, accordingly, is lateraly restrained or confined Within the mold, which preferably is controlled to provide a clearance of less than about 0.005 inch relative to the surfaces of the blank. The mold 60* is also preferably provided with a retaining ring 62 therearound for reinforcing and preventing any lateral deflection of the mold during the imposition of forces thereagainst during the cold extrusion operation.

The mold containing a blank is thereafter placed on a lower platen or shoe 64 of a press and is positioned such that the central bore 48 is disposed in axial alignment with a stepped die cavity 66 therein. The periphery of the die cavity 66 is of a diameter corresponding to the diameter of the periphery 50 of the tubular projection to be formed and is of a depth corresponding to the intended length thereof. The cavity 66 further includes a centrally aligned bore 68 for receiving the end of a circular stepped punch 70.

With the mold and the blank in appropriate registration relative to the cavity 66, an upper platen or shoe 72 of the press is lowered, whereby alignment pins- 74 are advanced into sliding contact within the apertures 28 thereof, effecting a concurrent retention of the aligned position, as well as effecting a confining of the blank against lateral deflection adjacent to the inner surfaces of these apertures. In this position, the stepped punch 40, which is aflixed to the end of a ram 76, is moved downwardly from the position as shown in solid lines in FIGURE 4 to a position as shown in phantom achieving a cold extrusion of the metal adjacent to the central bore in an axial direction inwardly of one end face of the blank and a concurrent formation of the tubular projection by the axial displacement of the metal. The length of stroke of the punch and the depth of the extrusion of metal defining the pilot bore 38 will vary depending upon the clearance relationship between the surface of the mold and alignment pins relative to the mating surfaces of the blanks. Such clearance volume will be filled during the initial phase of the cold extrusion operation, whereafter the tubular projection is formed. It is for this reason that the clearance of the mold and alignment pin surfaces relative to the blank are preferably controlled to less than about 0.005 inch, minimizing the clearance volume.

The stepped punch 70 is provided with a lower cylindrical section 78 which is of a diameter corresponding substantially to the diameter of the bore 48 provided in the blank. The upper cylindrical section 80 of the stepped punch is of a diameter corresponding substantially to that of the desired pilot bore diameter of the finished fan spacer. Accordingly, during the cold extrusion operation, the pilot bore and the tubular projection are concurrently formed to the appropriate diameter and length, necessitating no further machining operations.

At the completion of the cold extrusion operation, the stepped punch is withdrawn, after which the upper shoe 72 is raised, effecting a withdrawal of the alignment pins from the preliminarily formed fan spacer. A suitable U-shaped ejector 77 is preferably provided'in the lower shoe 64 for lifting or extracting the blank and mold assembly from the die cavity 66 preparatory to the next operation.

Due to the flow of metal during the cold extrusion operation, some distortion of the end faces of the blank may occur. In order to assure accurate alignment and parallelism of the end faces 32 and 34 relative to the longitudinal axis of the fan spacer, it is preferred to subject the cold extruded blank to a coining operation as illustrated in FIGURE 5. As shown in FIGURE 5, the preliminary formed spacer retained within the mold 60 is placed on a lower die shoe 82 incorporating a cavity 84 for receiving the tubular projection in clearance relationship. A suitable upper shoe or ram 86 thereafter is lowered so as to strike the upper end face 32, effecting a compacting or coining of the end faces of the blank, assuring a parallelism thereof preferably within at least about 0.003 inch.

At the completion of the coining operation, the fan spacer is pressed from the mold and is in condition for use without any further machining or finishing operations.

An alternative satisfactory die assembly and fan spacer in accordance with another embodiment of the present invention are illustrated in FIGURES 6 and 7. The fan spacer as illustrated in FIGURES 6 and 7 is similar to that previously described with the exception that the configuration of the die is such that the cold extrusion of the blank is accomplished in a manner so as to form a cylindrical projection which is of a solid as opposed to a tubular construction. As shown in FIGURE 7, the fan spacer 88 similarly is provided with a plurality of radially spaced and longitudinally extending throughbolt holes 90 extending through tubular bosses 92, which are connected by means of webs 94 to a central tubular boss 96, and an enlarged pilot bore 98 extends concentrically to the longitudinal axis of the fan spacer inwardly from one end face thereof and is disposed in communication with a bore 100 of a smaller diameter disposed concentric therewith, forming an annular shoulder 102 at the intersection therebetween. The bore 100 terminates at a point spaced from an end face 104 of a cylindrical projection 106 projecting outwardly of the other end face of the fan spacer and substantially concentric to and in alignment with the longitudinal axis thereof. The end wall 108 of the cylindrical projection 106 is formed during the cold extrusion of the metal blank wherein the original central bore 100 is filled with extruded metal during the inward movement of a stepped punch 110, as shown in FIGURE 6, in a manner as previously described. The fan spacer 88, as illustrated in FIGURE 7, in other respects is substantially identical to the fan spacer 8 illustrated in FIGURE 3, as previously described, and preferably is subjected to a coining operation to provide parallelism of the end faces of the fan spacer, as Well as a suitable heat treatment, if of an appropriate alloy, either prior to the cold extrusion operation or at the completion of the formation of the part.

The die assembly, as illustrated in FIGURE 6, includes a mold 112 similar to the mold 60 previously described in which the blank is laterally confined during the cold extruding step. Alignment pins 114 are held in a punch retainer 118 aflixcd to an upper die shoe or platen 116 and are of a length so as to be disposed within the through-bolt holes of the blank, providing lateral confinement of the material adjacent thereto prior to the extruding action as imposed by the downward stroke of the stepped punch 110. The stepped punch similarly is afiixed to the upper punch retainer 118 in vertical alignment with the original bore 100 in the blank, as indicated in phantom in FIGURE 6. The punch retainer is secured to the upper die shoe 116 by means of dowels 120 and screws 122.

The mold 112 is seated in appropriate aligned relationship on a die 124 seated on a lower platen or shoe 126, which incorporate aligned apertures 128, 130, respectively, for slidably receiving the projecting end portions of the alignment pins 114. The central portion of the die 124 is provided with a cylindrical centrally disposed cavity 132 into which the metal is extruded during the downward movement of the punch. The cavity conforms to the size and configuration of the cylindrical projection 106 desired to be provided on the fan spacer.

While it will be apparent that the preferred embodiments of the invention herein disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope of fair meaning of the subjoined claims.

What is claimed is:

1. The method of making an integral fan spacer which I comprises the steps of extruding a billet of an extrudable metal into a rod of indefinite length having a substantially constant cross section and incorporating a centrally extending longitudinal bore and a plurality of longitudinally extending circumferentially spaced apertures, severing said rod substantially perpendicular to the longitudinal axis thereof forming a plurality of individual blanks of a preselected length, confining the periphery of a blank in a mold, and cold extruding the material adjacent to said bore in an axial direction inwardly of one end face thereof forming a pilot bore of a preselected diameter and depth disposed concentric to said bore and simultaneously forming a cylindrical projection extending outwardly of the other end face and concentric to said bore.

2. The method as defined in claim 1, wherein the confining surfaces for confining the periphery of said blank are disposed at less than about 0.005 inch from the surfaces of said blank.

3. The method as defined in claim 1, further including the step of heat treating said rod prior to said severing operation.

'4. The method as defined in claim 1, further including the step of compacting said blank in a longitudinal direction to position the end faces thereof in substantial parallelism.

5. The method as defined in claim 1, wherein said cold extruding step is performed wherein said longitudinal bore extends through said cylinder projection and concentric with the periphery thereof.

6. The method as defined in claim 1, wherein said cold extruding step is performed in a manner effecting a displacement of metal filling said longitudinal bore adjacent to the projecting face surface of said cylindrical projection and defining therewith an end wall.

References Cited UNITED STATES PATENTS 3,372,460 3/1968 Burns 29417 2,833,573 5/1958 Bagley 28752.04 2,088,223 7/1937 Witte 72267 3,442,000 5/1969 Dorabos 29175 CHARLES W. LANHAM, Primary Examiner A. L. HAVIS, Assistant Examiner US. Cl. X.R. 

